Fluid pumps and motors



Feb. 28, 1967 R. D. WALTER 3,306,226

FLUID PUMPS AND MOTORS Filed Feb. 23, 1965 /N van-0R BEHT Demus WALTE @sen' United States Patent 3,306,226 FLUID PUMPS AND MOTORS Robert Dennis Walter, Allesley, (Coventry, England, assignor to Concentric (Engineering) Limited, Birmingham, England, a British company Filed Feb. 23, 1965, Ser. No. 434,305 Claims priority, application Great Britain, Mar. 26, 1964, 12,923/64 1 Claim. (Cl. 103-126) This invention relates to fluid pumps and motors.

There are, inter alia, two well-known kinds of fluid pumps and motors, namely the rotor and vane kinds. The rotor kind utilises a lobed hub which is shaped substantially complementary to the inner periphery of an annular ring, for example is star-shaped, but is smaller than the ring so that during rotation about an axis the annulus rotates about an eccentric axis. In the vane kind the hub carries a plurality of blade-like vanes which slide radially of the hub inwards and outwards as the hub rotates in a stationary chamber. In either case, a plurality of separate pockets, i.e. inter-lobe or inter-vane spaces are created, and these vary in volume during the rotation. Hence if pressurised fluid is admitted near the minimum volume point to expand in the pocket as the rotation continues, work is done and the construction operates as a motor: again, if fluid is admitted near the point of minimum volume then it is pressurised during the rotation and the construction acts as a pump.

Both of these kinds of pumps or motors have known advantages and disadvantages, and suit different requirements, and the objects of the present invention are to provide a new pump or motor which is advantageous from at least some aspects over the hitherto known pumps and motors of these kinds.

In accordance with the present invention a pump or motor comprises a hub provided with a plurality of slidable vanes, the hub and vanes together constituting a lobed rotor, and a rotatable annulus having its inner periphery which co-operates with the rotor of substan tially complementary shape.

Hence the invention utilises the rotatable annulus and complementary shaped hub of the one known kind of pump or motor and the slidable vanes of the other known kind. This enables higher pressures to be utilised or obtained than in the case with known constructions, for rotor clearances limit the possible pressures without leakage between successive chambers in conventional constructions and where the hub rotor is used in conventional constructions great accuracy is necessary in machining the parts so that in mass production techniques designs have to be limited to exclude high pressures: furthermore the invention reduces the relative sliding action compared with pure vane pumps since in a construction according to the invention the vane ends move at the speed ratio of the number of teeth, and consequently move one annulus tooth space per revolution instead of sliding the full 360.

The invention is applicable to odd and even lobe numbers on the hub and annulus.

Preferably a communication is establishd between the pressurised fluid and the root of each hub slot which accommodates a vane, so that the vanes are urged outwards by the fluid pressure assisted by centrifugal force: this takes up the running clearances and ensures good contact between the vane tips and the annulus Wall, and moreover, because the pressure is equal to or greater than the pocket pressure, prevents leakage between pockets via the annulus clearances.

The tip of each vane may be conjugate with respect of the lobe shapes of the annulus, but this is not essential as 3,306,226- Patented Feb. 28, 1967 the construction is largely self-adjustingz hence tolerances permissible in manufacture are wide, this being of material importance in enabling production to be cheapened.

The vanes may have a pure sliding action or may be rollers which have roll-contact with the annulus wall instead of sliding thereon, and if desired the vanes may be spring-urged outwards as well as fluid pressure urged.

The spacing between the axes of the hub and annulus may be variable, and in general reduction towards zero spacing, i.e. co-axiality, reduces the extent of variation of inter-lobe volumes, and hence reduces the output of the pump or speed of the motor: at co-axiality, the output or speed is at a minimum or zero. Further movement of the annulus beyond the zero position will reverse the flow conditions without the necessity of reversing the inlet and outlet connections. Hence, the invention in such case provides a pump or motor which is adjustable for output and/or pressure, or which can be put into neutral condition, by a simple movement of the parts in the direction of a line joining their axes.

The drawing illustrates diagrammatically, in two positions of movemnt, a construction of the invention.

In the drawing the hub 10 is shaped substantially complementary (with its vanes 11) to the interior form of the annulus ring 12 except that the hub has six lobes (i.e. the number N of ring pockets minus one). Each lobe carries a sliding vane which has two parallel flat faces slidably engaging corresponding faces of a slot in the associated lobe and connected by an exposed contact face of semicircular cross section which engages the ring 12. The vane slot roots 14 communicate with the pressurised fluid which is pumping the motor or being pumped by the pump as the case may be so as to equalise pressures within the root slots and in the high pressure zone 15 of the construction.

It will be realised by those skilled in the art that relative rotation is required and this may take the form of rotation of either the hub and vanes or the ring or both in either, both or even the same direction. The maximum eccentricity at between centres results in maximum work performance, although obviously rotation of both ring and hub in the same direction at the same speed results in zero or more condition, irrespective of eccentricity. The eccentricity is variable in the direction of arrow A and even reversible, i.e. movable beyond the position of co-axiality or concentricity.

I claim:

A pump or motor comprising a hub provided with a plurality of slidable vanes, the hub and vanes together constituting a lobed rotor, and a rotatable annulus having its inner periphery which co-operates with the rotor of substantially complementary shape, the hub having an axis and being formed with a plurality of slots angularly offset about said axis, the hub having two flat parallel facs in each slot, each slot receiving one of said vanes, the vane having two parallel flat faces slidably engaging the faces of the hub in the associated slot, and a contact face of semicircular cross section, said contact face connecting said flat faces of said vane and movably engaging said annulus during rotation of said rotors.

References Cited by the Examiner UNITED STATES PATENTS 1,486,835

DONLEY I. STOCKING, Primary Examiner. WILBUR I. GOODLIN, Examiner. 

